ERBIL, Kurdistan Region of Iraq - Baghdad sent a protest letter to the US-led Global Coalition against the Islamic State (ISIS) after a suspected coalition operation in Najaf province led to a skirmish that saw the killing of one Iraqi soldier and injured two others, an official said on Thursday.

“We received reports of individuals or movement in the Najaf desert, near the borders of Karbala. A force comprised of three regiments from the Karbala Operations Command was deployed to investigate,” Qais al-Muhammadawi, Iraq's Deputy Commander of Joint Operations Command, said, according to state media.

“The force came under heavy aerial fire, resulting in the death of one fighter and injuries to two others,” he added.

Muhammadawi stressed that there has been no approval for any force to have a presence at the location and that the force in question was either attempting to support reconnaissance operations or install equipment.

“The Popular Mobilization Forces [PMF] are part of a security apparatus that operates under the command of the Commander-in-Chief of the Armed Forces, and we have issued an order for the security forces to be present in all areas, including desert regions, with intensified patrols,” he said.

While mentioning the PMF, the precise nature of the operation in question remains unclear.

The US and Israel have conducted airstrikes against pro-Iran Iraqi groups under the PMF banner since the beginning of the military campaign against Iran, while Iran has attacked US interests across the region.